The present invention relates to an image forming method and an image forming apparatus, and specifically to improvement in the relationship between the reference position in which an original document is read and its image processing.
In copying apparatuses and scanners, there are one case in which an original document is placed on a glass platen and is read, and also another case in which the original document is conveyed onto the glass platen by an automatic document feeder (ADF) and is then read.
Further, by employing an apparatus called a duplex document feeder (DDF), an original document under conveyance may be read while holding the image sensor.
Further, when an original document is placed on the glass platen, the reference position for placing the original document may be either at one edge of the glass platen or at the center thereof. Furthermore, when an original document is conveyed employing ADF or DDF, the reference position for conveying the original document is in the same manner, namely either at one edge of the glass platen, or at the center thereof.
In ADF and DDF, when conveyance is carried out utilizing the center of the conveyance path as the reference, stable conveyance may be achieved because conveyance force can be evenly applied to both the right and left sides of an original document, to tend to result in linear motion. On the other hand, when the original document is placed on the glass platen while employing one edge of the glass platen as the reference position for placement of the same, it is possible to provide a positioning member at the edge thereof and to position the original document while being brought into close contact with the edge of the member. Thus, positioning is readily carried out and operability is enhanced. Based on these factors, Japanese Patent Publication Open to Public Inspection No. 7-336522 discloses that the reference position is altered in such a manner that when conveyed by ADF, the center is utilized as the reference, and when an original document is placed on the glass platen, one edge of the glass platen is employed as the reference position.
In such a case, the reference position of image data read from an original document placed on the glass platen is different from that of image data read from an original document conveyed by ADF and DDF. As a result, variable magnification process (enlarging process and reduction process) becomes complicated.
Further, when mixed-size original documents are successively read employing DDF or ADF provided with a pair of guide plates which are symmetrically widened in equal amounts of movement from the center to both sides, small-sized original documents are positioned so as to be in contact with one of the guide plates. Namely, there may exist original documents which are positioned in the center reference and are deviated somewhat from the center.
When image data generated by reading such mixed-size original documents are subjected to variable magnification process, the process becomes complicated due to the required correction of the reference position. Further, when the sizes of original documents are different, the process becomes more complicated due to the difference in a correction amount according to the difference in size.
In view of the above-mentioned technical problems, the present invention is accomplished. An object of the present invention is to provide an image forming method and an image forming apparatus in which an original document conveying means is employed, which is comprised of a pair of original document guides which are symmetrically widened from the center to both sides in equal amounts of movement, and the original document under conveyance is read, and when variable magnification process is carried out, no further complicated process is required.
The above-mentioned problems can be solved by the following structure and the following method:
An image forming apparatus comprises:
a document feeder having a stand on which documents are placed and a pair of guide plates which move from a center of the stand to sides of the stand, whereby the document feeder feeds a document by using the pair of guide plates in such a way that the center of the document is moved approximately along the center of the stand;
an image reader to read the document so as to obtain document-shaped image data; and
an image processor having a memory region to store the document-shaped image data, the memory region having a width whose center is arranged to approximately conform with the center of the document-shaped image data;
wherein when the image processor conducts an image processing, the image processor shifts the document-shaped image data toward one side of the memory region so that one side of the document-shaped image data is approximately conformed with a reference side of the memory region.
An image forming method, comprises steps of:
feeding a document placed on a stand by using a pair of guide plates which move from a center of the stand to sides of the stand in such a way that the center of the document is moved approximately along the center of the stand;
reading an image on the document by a reading section so as to obtain document-shaped image data; and
storing the document-shaped image data in a memory region having a width whose center is arranged to approximately conform with the center of the document-shaped image data; and
shifting the document-shaped image data toward one side of the memory region when the image processor conducts an image processing so that one side of the document-shaped image data is approximately conformed with a reference side of the memory region.
Further, the above-mentioned problems may be solved by the following preferable structure and the following preferable method:
(1) an image forming method characterized in that an original document is conveyed employing a pair of original document guides which are symmetrically widened from the center to both sides in equal amounts of movement, image data are generated while reading the original document under conveyance, and after shifting the generated image data of said original document to the reference edge, image processing is executed.
Furthermore, an image forming apparatus characterized in comprising an original document conveying means employing a pair of original document guides which are symmetrically widened from the center to both sides in equal amounts of movement, a reading means which reads the original document under conveyance employing the above-mentioned original document conveying means, and an image processing means which shifts the original document image data generated by the above-mentioned reading means to the reference edge, and executes image processing.
In these inventions, when image data are generated by reading the original document under conveyance employing a pair of original document guides which are symmetrically widened from the center to both sides in equal amounts of movement, image processing is executed after shifting the generated original document image data to the reference edge side. Thus calculation in data processing for image processing such as variable magnification process will be readily carried out. Further, even for mixed-size original documents, position correction is not required because original documents are shifted to the reference edge.